Steve,
What you've described is unclear to me. You're dragging a folder in the Navigator or Favorites in PM Plus to where? Another folder in the Favorites or Navigator in PM Plus? Another Or outside to another application like Windows Explorer (on Windows) or Finder (macOS) ? If you're dragging outside of PM Plus, then PM Plus isn't doing the copy/move operation and is unaware of the new location.
I think you may be better off only adding your items to your catalog once they have been moved to their final destination.
HTH,
-Kirk